Project Summary/Abstract Pulmonary hypertension (PH) is a debilitating and often fatal disease for which there is currently no cure. The environmental and genetic factors that drive susceptibility to the development of PH and responses to therapy are poorly understood. This observation is particularly true in specific demograghic (i.e. male) and clinical (i.e. scleroderma) cohorts noted to experience greater risk and severity of PH. Additionally, little is known about the impact of ethnicity on disease severity These information gaps are exacerbated by the perplexing assortment of clinical characteristics, histopathological entities and responses to therapy that constitute the 5 categories within the current World Symposium classification of PH patients. While providing a framework for the diagnosis and treatment, the current classification has serious limitations in clinical practice. Derived in part from functional measurements with limited predictive ability, more disease-specific measurements are needed that predict survival, quality of life, progression and response to therapy. The University of Arizona (UA) Medical Center is a major regional referral center for treatment of patients with PH, including a large population of Latino PH patients. Our program has an over-representation of Latinos with PH across all 5 Groups (25% Latinos with high Native American admixture with Group 1-PH). Based on our exceptionally strong published sub-phenotyping studies in well-defined PH subgroups (CTEPH, PH-associated with sickle cell disease) and patients with complex lung disorders (sarcoidosis, IPF, lung transplant), we propose to employ the state-of-the-art physiologic, genomic and epigenetic strategies to sub-phenotype Latino and non-Latino PH patients across the 5 PH categories. SA #1 will leverage our advanced diagnostics clinical algorithm, incorporating cardiac MRI, echocardiography, and catheterization to reliably measure ventriculo- vascular coupling (VVC) and pulmonary vascular impedance and cardiopulmonary exercise tesing to physiologically phenotype Latino and non-Latino PH patients across all Group 1-5 PH phenotypes. SA #2 will generate genome-wide, genetic/epigenetic molecular signatures in peripheral blood mononuclear cells (PBMCs) to sub-phenotype PH patients across all 5 WHO PH categories. These studies will include genome- wide gene expression, miRNA arrays, and DNA methylation arrays. SA #3 will extend out prior studies utilizing genome-wide association studies (GWAS) in patients with idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) and utilize whole-genome sequencing to identify novel single nucleotide polymorphisms (SNPs) that are over-represented in Latinos with category- specific PH. We will further examine the relationship of SA #1-3 to the clinically important composite variable, time to clinical worsening (TTCW). Together, the large UA pool of diverse PH patients, large PH referral base, comprehensive UA BioBank initiative, and prior experience with these phenotyping tools, all serve to increase the feasibility of our novel sub-phenotyping strategy focusing on Latinos with PH. These highly translational studies will generate novel category-specific biomarkers in this devastating pulmonary vascular disease and hold promise for a) identifying groups at high-risk for development of PH, b) personalizing PH therapies (combination therapy, transplant or surgical referral), and c) providing the rationale for novel PH classification paradigms.